Method of making abrasive material.



UNITED sTATEs PATENT OFFICE.

HERBERT T. KALMUS, 0F BROOKLINE, MASSACHUSETTS, ASSIGNOB TO THE EXOLON COMPANY, OF CAMBRIDGE. MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

METHOD OF MAKING ABRASIVE MATERIAL.

No Drawing. 7

To all whom it may concern.

Be it known that I, HERBERT T. KALMUS, a citizen of the United States, residing at Brookline, in the county of Norfolk and State of Massachusetts, have invented certain newv and useful Improvements in Methods of Making Abrasive Material ,and I do I hereby declare the following to'be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it'appertains to make and use the same.

The present invention relates to an improved method ofmaking abrasive material.

The object of the invention is to produce an abrasive material, preferably an aluminous abrasive material of superior hardness toughness, density and abrasive qualities, an to this end the invention consists in the abrasive material and the method of making it hereinafter described and particularly defined in the claims.

Heretofore, aluminous material fused in arc-type electric-furnaces to produce abra sives has been permitted to cooland solidify in the furnace. Such cooling has, at best, been slow, and the product, while suitable for certain abrasive uses, has left many demands of the users of abrasives unfilled, owing to its large-grained structure, its lack of homogeneity, toughness and denseness and because ofitsiunsatisfactory manner of fracture. It has been proposed to improve the quality ofthe product by subjecting the exterior of the furnace to the cooling effect of water. However, the furnace was of such size and the body of material so large, that even such additional application of water for the purpose of mcreasing the rate of cooling has been insufiicient to produce the desired qualities inthe product. The fused mass itself, as it solidifies upon its'surface, affords a shell which retards the loss of heat by the mass, with the result that although the outer portions of the mass are more or less quickly cooled, the body of the mass itself cools but slowly, owing to the impediment to loss of heat I which thesolidified shell of the mass preisproduced, having new sents. I have discoveredthat a new product and vastly superior abrasive roperties, by making provision for cooling 1; e fused *materials in bodies of small ratio of mass to superficial area and Speeification of Letters Patent.

a place where it layer upon layer,

Patented May 22,1917.

Application filed May 7, 1915. Serial No. 26,626.

such that the average distance of the elements of the mass to the surface is as small as possible, so as thereby to permit the loss of heat at such a rate as to secure hardness, toughness, denseness, a, fine-grained crystalline structure, a satisfactory fracture and abrasive properties in the product, as distinguished from a more friable, less dense, larger-grained product with unsatisfactory fracture heretofore obtained. To cause these" masses to lose heat at the greatest rate the ratio of mass to superficial area must be as small as possible to assist radia tion, and the average distance of the elements of the mass from the surface must be as small as posslble to assist conduction 'and convection within the mass. Wherever tude of the average distance of the mass from the surface. The best way of cooling the fused mass is to draw it from the furnace, pouring or casting it into a moving mold, or pouring or casting it from a moving, furnace, or pouring or casting it into a receptacle by directing the stream to different parts of thereceptacle, successively, so as thereby to expose the fused substance to the cooling action of the air as it is poured, and to expose it in thin layers after it has fallen into the receptacle. Layer after layer may be poured into the receptacle so that the material cools layer by layer.

The present invention contemplates the fusing of various substances from which abrasive material is to be formed, and is not limited to the use of any particular material. The preferred method of carrying out the process consists in fusing basic aluminum sulfite, or an equivalent substance, in an arc-type electric furnace, and in tapping off the fused alumina into, a receptacle and in pouring the fused material from suchreceptacle in a thin or slender stream onto rate by conduction and. convection of heat within the mass and by radiationin air, or other cooling medium, in thin layers, and

ing poured upon previously solidified layers.

may cool at the maximum the succeeding layers. be-

If desired, the material may be poured upon the particles break with terial presents a greater a floor constructed of refractory material, and built up layer on layer as it cools. If desired, the cooling may take place in a draft of air, so as thereby to' secure rapid cooling effect.

Another method of practising the invention consists in fusing, in an arc-type electric furnace, emery. mixed with carbon, forming fused almina containing small. but important percentages of other oxide, as, for example, titanium oxid, silica and iron oxid after the well known method, and in drawing off the aluminous material and pouring it in a slender stream and allowing it to cool layer upon layer, as above described.

The important feature of my improved method resides in cooling the fused material in bodies of small ratio of mass to superficial area, as by pouring the fused material in a thin or slender stream andallowing it to cool in layers-and preferably layer upon layer.

extraordinarily dense, and exceptionally fine-grained crystalline abrasive product, which is especially available for use in the manufacture of grinding wheels wherein the individual grains or kernels of the material are embedded in a bonding material and offer sharp projections'from the working'face of the wheel which form cutting edges. These projections possess sufficient strength to perform their-cutting or grinding work under the conditions of use until the cutting edges become dulled, whereupon a sharp cutting and abrasive fracture presenting new cutting edges resembling the original cutting edges of the grains. The material has abrasive toughness, that is, resistance to fracture by compression, and in use the cutting edges are renewed by the breaking of the particles with an abrasive fracture. Owing to the fineness of the crystalline structure, the manumber of cutting edges than a coarser gra'ined material and further contributes to the rapid renewal of the cutting edges under abrasive work. The

qualities of abrasive toughness, denseness, fine-grainedcrystalline structure and abrasive fracture contribute to the durability and abrasive qualities of the material when used for abrasive purposes. These proper ties distinguish this product from'products cooled in greater masses, and especially products cooled in a furnace in large masses. This product is, to a large degree, homogeneous as a result of the manner of cooling which prevents thesegregation of impurities. It is also substantially free from reduction products, such as the sub-oxide and carbids, owing, it is believed, to the short period of time for which the fused mass is held at ahigh temperature.

The resultin product of the method' hereinbefore descrl ed is an exceedingly tough,

' on the stream as it is poured.

Having thus described is claimed is 1. The method of making abrasive material which consists in fusing the substance of extremely high melting point or subthe invention, what pouring it in a slender stream and solidifying it in layers of small ratio of mass to superficial area.

3. The method ofmaking abrasive material which consists in fusing the substance of extremely high melting point or sub-' stances from which the'material is. to be formed and cooling the fused substance by pouring it in layers and allowing it to cool layerby layer.

4- The method of making abrasive material which consists in fusing aluminous material and cooling the fused material by pouring it in layers and allowing it to cool layer by layer.

5. The method of making abrasive material which comprises fusing the substance or substances from which the material is to be formed in an electric furnace, and in cooling the material upon a cooling receiverby pouring the material from the furnace u on the receiver and relatively moving the rnace and the receiver during the pouring operation to distribute the material in a thin layer.

6. The method of making an aluminous abrasive which comprises fusing the aluminous material in anelectricfurnace and in cooling the fused material upon a cooling receiver by pourin the material in slender streams from the urnace upon the receiver and relatively moving the furnace andthe receiver during the pouring operation to distribute the material in a thin layer upon the receiver.

7. The -method of making an aluminous. abrasive which comprises fusing the aluminous material in an electric furnace and in pouring the fused material in a slender stream upon a mold which is being moved 'past the furnace during. thepouring operabrasive which comprises fusing the aluminous material in an electric furnace, pourmg the materialln a slender stream upon a moving mold, 311C111} directing a cooling gas 9. The method of making an aluminous abrasive which comprises fusing the aluminous material in an electric furnace, pouring the fused material onto a cooling re- 70 stances fromfwhlch the abrasive material 1s ceiver, and moving the receiver to distribute the material layer upon layer thereon.

10. The method of making abrasive material which consists in fusing aluminous material in an electric furnace at such temperatures and under such conditions as to prevent the formation of sub-oxide and carbids and other reduction products, and to secure homogenelty to a. large degree, by drawing off the fused material as formed and pouring 10 it in bodies of small ratio of mass to superficial area, to stir or mix the mass while cooling in HERBERT T. KALMUS.

It is hereby certified that in Letters Patent No. 1,226,892, granted May 22, l9l7,

upon the application of Herbert T. Kalmus, of Brookline, Massachusetts, for an improvement in Methods of Making Abrasive Material, errors appear in the printed specification requiring correction as follows: Page 2, line 69, claim 1, and

line 83, claim 3, alter the word substance insert the words or substances; same page, lines 70-71, claim 1, and lines 84-85, claim 3, strike out the words "or substances; and that the said Letters Patent should be read with these corrections therein that the some may conform to the record of the case in the Patent Oflice.

Signed and sealed this 26th day of June, A. D 1917.

R. F. WHITEHEAD, Acting Commissioner of Patents.

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